/*
 * Copyright (c) 1985, 1993
 *    The Regents of the University of California.  All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 * 	This product includes software developed by the University of
 * 	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
 * 
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies, and that
 * the name of Digital Equipment Corporation not be used in advertising or
 * publicity pertaining to distribution of the document or software without
 * specific, written prior permission.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

/*
 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

/* Original copyright ISC as above. 
 * Code modified specifically for ircd use from the following orginal files
 * in bind ...
 *
 * res_comp.c
 * ns_name.c
 * ns_netint.c
 * res_init.c
 * 
 * - Dianora
 */

#include "stdinc.h"
#include "irc_reslib.h"
#include "irc_res.h"
#include "ircd_defs.h"
#include "fileio.h"
#include "irc_string.h"
#include "irc_getaddrinfo.h"

#define NS_TYPE_ELT             0x40	/* EDNS0 extended label type */
#define DNS_LABELTYPE_BITSTRING 0x41
#define MAXLINE 128

/* $Id: irc_reslib.c 417 2006-07-08 06:51:30Z jon $ */

struct irc_ssaddr irc_nsaddr_list[IRCD_MAXNS];
int irc_nscount = 0;
char irc_domain[HOSTLEN + 1];

static const char digitvalue[256] = {
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,	/*16 */
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,	/*32 */
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,	/*48 */
	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,	/*64 */
	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,	/*80 */
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,	/*96 */
	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,	/*112 */
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,	/*128 */
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,	/*256 */
};

static int parse_resvconf(void);
static void add_nameserver(char *arg);

static const char digits[] = "0123456789";
static int labellen(const unsigned char *lp);
static int special(int ch);
static int printable(int ch);
static int irc_decode_bitstring(const char **cpp, char *dn, const char *eom);
static int irc_ns_name_compress(const char *src, unsigned char *dst, size_t dstsiz,
				const unsigned char **dnptrs, const unsigned char **lastdnptr);
static int irc_dn_find(const unsigned char *, const unsigned char *, const unsigned char *const *,
		       const unsigned char *const *);
static int irc_encode_bitsring(const char **, const char *, unsigned char **, unsigned char **,
			       const char *);
static int irc_ns_name_uncompress(const unsigned char *, const unsigned char *,
				  const unsigned char *, char *, size_t);
static int irc_ns_name_unpack(const unsigned char *, const unsigned char *,
			      const unsigned char *, unsigned char *, size_t);
static int irc_ns_name_ntop(const char *, char *, size_t);
static int irc_ns_name_skip(const unsigned char **, const unsigned char *);
static int mklower(int ch);

int
irc_res_init(void)
{
	irc_nscount = 0;
	return parse_resvconf();
}

/* parse_resvconf()
 *
 * inputs - NONE
 * output - -1 if failure 0 if success
 * side effects - fills in irc_nsaddr_list
 */
static int
parse_resvconf(void)
{
	char *p;
	char *opt;
	char *arg;
	char input[MAXLINE];
	FBFILE *file;

	/* XXX "/etc/resolv.conf" should be from a define in setup.h perhaps
	 * for cygwin support etc. this hardcodes it to unix for now -db
	 */
	if((file = fbopen("/etc/resolv.conf", "r")) == NULL)
		return -1;

	while(fbgets(input, sizeof(input), file) != NULL)
	{
		/* blow away any newline */
		if((p = strpbrk(input, "\r\n")) != NULL)
			*p = '\0';

		p = input;

		/* skip until something thats not a space is seen */
		while(IsSpace(*p))
			++p;

		/* if at this point, have a '\0' then continue */
		if(*p == '\0')
			continue;

		/* Ignore comment lines immediately */
		if(*p == ';' || *p == '#')
			continue;

		/* skip until a space is found */
		opt = p;
		while(!IsSpace(*p) && *p)
			++p;

		if(*p == '\0')
			continue;	/* no arguments?.. ignore this line */

		/* blow away the space character */
		*p++ = '\0';

		/* skip these spaces that are before the argument */
		while(IsSpace(*p))
			++p;

		/* Now arg should be right where p is pointing */
		arg = p;

		if((p = strpbrk(arg, " \t")) != NULL)
			*p = '\0';	/* take the first word */

		if(irccmp(opt, "domain") == 0)
			strlcpy(irc_domain, arg, HOSTLEN);
		else if(irccmp(opt, "nameserver") == 0)
			add_nameserver(arg);
	}

	fbclose(file);
	return 0;
}

/* add_nameserver()
 *
 * input        - either an IPV4 address in dotted quad
 *                or an IPV6 address in : format
 * output       - NONE
 * side effects - entry in irc_nsaddr_list is filled in as needed
 */
static void
add_nameserver(char *arg)
{
	struct addrinfo hints, *res;
	/* Done max number of nameservers? */
	if((irc_nscount) >= IRCD_MAXNS)
		return;

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = PF_UNSPEC;
	hints.ai_socktype = SOCK_DGRAM;
	hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST;

	if(irc_getaddrinfo(arg, "domain", &hints, &res))
		return;

	if(res == NULL)
		return;

	memcpy(&irc_nsaddr_list[irc_nscount].ss, res->ai_addr, res->ai_addrlen);
	irc_nsaddr_list[irc_nscount].ss_len = res->ai_addrlen;
	irc_nscount++;
	irc_freeaddrinfo(res);
}

/*
 * Expand compressed domain name 'comp_dn' to full domain name.
 * 'msg' is a pointer to the begining of the message,
 * 'eomorig' points to the first location after the message,
 * 'exp_dn' is a pointer to a buffer of size 'length' for the result.
 * Return size of compressed name or -1 if there was an error.
 */
int
irc_dn_expand(const unsigned char *msg, const unsigned char *eom,
	      const unsigned char *src, char *dst, int dstsiz)
{
	int n = irc_ns_name_uncompress(msg, eom, src, dst, (size_t) dstsiz);

	if(n > 0 && dst[0] == '.')
		dst[0] = '\0';
	return (n);
}

/*
 * irc_ns_name_uncompress(msg, eom, src, dst, dstsiz)
 *	Expand compressed domain name to presentation format.
 * return:
 *	Number of bytes read out of `src', or -1 (with errno set).
 * note:
 *	Root domain returns as "." not "".
 */
static int
irc_ns_name_uncompress(const unsigned char *msg, const unsigned char *eom,
		       const unsigned char *src, char *dst, size_t dstsiz)
{
	unsigned char tmp[NS_MAXCDNAME];
	int n;

	if((n = irc_ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
		return (-1);
	if(irc_ns_name_ntop((char *) tmp, dst, dstsiz) == -1)
		return (-1);
	return (n);
}

/*
 * irc_ns_name_unpack(msg, eom, src, dst, dstsiz)
 *	Unpack a domain name from a message, source may be compressed.
 * return:
 *	-1 if it fails, or consumed octets if it succeeds.
 */
static int
irc_ns_name_unpack(const unsigned char *msg, const unsigned char *eom,
		   const unsigned char *src, unsigned char *dst, size_t dstsiz)
{
	const unsigned char *srcp, *dstlim;
	unsigned char *dstp;
	int n, len, checked, l;

	len = -1;
	checked = 0;
	dstp = dst;
	srcp = src;
	dstlim = dst + dstsiz;
	if(srcp < msg || srcp >= eom)
	{
		errno = EMSGSIZE;
		return (-1);
	}
	/* Fetch next label in domain name. */
	while((n = *srcp++) != 0)
	{
		/* Check for indirection. */
		switch (n & NS_CMPRSFLGS)
		{
		case 0:
		case NS_TYPE_ELT:
			/* Limit checks. */
			if((l = labellen(srcp - 1)) < 0)
			{
				errno = EMSGSIZE;
				return (-1);
			}
			if(dstp + l + 1 >= dstlim || srcp + l >= eom)
			{
				errno = EMSGSIZE;
				return (-1);
			}
			checked += l + 1;
			*dstp++ = n;
			memcpy(dstp, srcp, l);
			dstp += l;
			srcp += l;
			break;

		case NS_CMPRSFLGS:
			if(srcp >= eom)
			{
				errno = EMSGSIZE;
				return (-1);
			}
			if(len < 0)
				len = srcp - src + 1;
			srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
			if(srcp < msg || srcp >= eom)
			{	/* Out of range. */
				errno = EMSGSIZE;
				return (-1);
			}
			checked += 2;
			/*
			 * Check for loops in the compressed name;
			 * if we've looked at the whole message,
			 * there must be a loop.
			 */
			if(checked >= eom - msg)
			{
				errno = EMSGSIZE;
				return (-1);
			}
			break;

		default:
			errno = EMSGSIZE;
			return (-1);	/* flag error */
		}
	}
	*dstp = '\0';
	if(len < 0)
		len = srcp - src;
	return (len);
}

/*
 * irc_ns_name_ntop(src, dst, dstsiz)
 *	Convert an encoded domain name to printable ascii as per RFC1035.
 * return:
 *	Number of bytes written to buffer, or -1 (with errno set)
 * notes:
 *	The root is returned as "."
 *	All other domains are returned in non absolute form
 */
static int
irc_ns_name_ntop(const char *src, char *dst, size_t dstsiz)
{
	const char *cp;
	char *dn, *eom;
	unsigned char c;
	unsigned int n;
	int l;

	cp = src;
	dn = dst;
	eom = dst + dstsiz;

	while((n = *cp++) != 0)
	{
		if((n & NS_CMPRSFLGS) == NS_CMPRSFLGS)
		{
			/* Some kind of compression pointer. */
			errno = EMSGSIZE;
			return (-1);
		}
		if(dn != dst)
		{
			if(dn >= eom)
			{
				errno = EMSGSIZE;
				return (-1);
			}
			*dn++ = '.';
		}
		if((l = labellen((unsigned char *) (cp - 1))) < 0)
		{
			errno = EMSGSIZE;	/* XXX */
			return (-1);
		}
		if(dn + l >= eom)
		{
			errno = EMSGSIZE;
			return (-1);
		}
		if((n & NS_CMPRSFLGS) == NS_TYPE_ELT)
		{
			int m;

			if(n != DNS_LABELTYPE_BITSTRING)
			{
				/* XXX: labellen should reject this case */
				errno = EINVAL;
				return (-1);
			}
			if((m = irc_decode_bitstring(&cp, dn, eom)) < 0)
			{
				errno = EMSGSIZE;
				return (-1);
			}
			dn += m;
			continue;
		}
		for((void) NULL; l > 0; l--)
		{
			c = *cp++;
			if(special(c))
			{
				if(dn + 1 >= eom)
				{
					errno = EMSGSIZE;
					return (-1);
				}
				*dn++ = '\\';
				*dn++ = (char) c;
			}
			else if(!printable(c))
			{
				if(dn + 3 >= eom)
				{
					errno = EMSGSIZE;
					return (-1);
				}
				*dn++ = '\\';
				*dn++ = digits[c / 100];
				*dn++ = digits[(c % 100) / 10];
				*dn++ = digits[c % 10];
			}
			else
			{
				if(dn >= eom)
				{
					errno = EMSGSIZE;
					return (-1);
				}
				*dn++ = (char) c;
			}
		}
	}
	if(dn == dst)
	{
		if(dn >= eom)
		{
			errno = EMSGSIZE;
			return (-1);
		}
		*dn++ = '.';
	}
	if(dn >= eom)
	{
		errno = EMSGSIZE;
		return (-1);
	}
	*dn++ = '\0';
	return (dn - dst);
}

/*
 * Pack domain name 'exp_dn' in presentation form into 'comp_dn'.
 * Return the size of the compressed name or -1.
 * 'length' is the size of the array pointed to by 'comp_dn'.
 */
static int
irc_dn_comp(const char *src, unsigned char *dst, int dstsiz,
	    unsigned char **dnptrs, unsigned char **lastdnptr)
{
	return (irc_ns_name_compress(src, dst, (size_t) dstsiz,
				     (const unsigned char **) dnptrs,
				     (const unsigned char **) lastdnptr));
}

/*
 * Skip over a compressed domain name. Return the size or -1.
 */
int
irc_dn_skipname(const unsigned char *ptr, const unsigned char *eom)
{
	const unsigned char *saveptr = ptr;

	if(irc_ns_name_skip(&ptr, eom) == -1)
		return (-1);
	return (ptr - saveptr);
}

/*
 * ns_name_skip(ptrptr, eom)
 *	Advance *ptrptr to skip over the compressed name it points at.
 * return:
 *	0 on success, -1 (with errno set) on failure.
 */
static int
irc_ns_name_skip(const unsigned char **ptrptr, const unsigned char *eom)
{
	const unsigned char *cp;
	unsigned int n;
	int l;

	cp = *ptrptr;

	while(cp < eom && (n = *cp++) != 0)
	{
		/* Check for indirection. */
		switch (n & NS_CMPRSFLGS)
		{
		case 0:	/* normal case, n == len */
			cp += n;
			continue;
		case NS_TYPE_ELT:	/* EDNS0 extended label */
			if((l = labellen(cp - 1)) < 0)
			{
				errno = EMSGSIZE;	/* XXX */
				return (-1);
			}

			cp += l;
			continue;
		case NS_CMPRSFLGS:	/* indirection */
			cp++;
			break;
		default:	/* illegal type */
			errno = EMSGSIZE;
			return (-1);
		}

		break;
	}

	if(cp > eom)
	{
		errno = EMSGSIZE;
		return (-1);
	}

	*ptrptr = cp;
	return (0);
}

unsigned int
irc_ns_get16(const unsigned char *src)
{
	unsigned int dst;

	IRC_NS_GET16(dst, src);
	return (dst);
}

unsigned long
irc_ns_get32(const unsigned char *src)
{
	unsigned long dst;

	IRC_NS_GET32(dst, src);
	return (dst);
}

void
irc_ns_put16(unsigned int src, unsigned char *dst)
{
	IRC_NS_PUT16(src, dst);
}

void
irc_ns_put32(unsigned long src, unsigned char *dst)
{
	IRC_NS_PUT32(src, dst);
}

/* From ns_name.c */

/*
 * special(ch)
 *      Thinking in noninternationalized USASCII (per the DNS spec),
 *      is this characted special ("in need of quoting") ?
 * return:
 *      boolean.
 */
static int
special(int ch)
{
	switch (ch)
	{
	case 0x22:		/* '"'  */
	case 0x2E:		/* '.'  */
	case 0x3B:		/* ';'  */
	case 0x5C:		/* '\\' */
	case 0x28:		/* '('  */
	case 0x29:		/* ')'  */
		/* Special modifiers in zone files. */
	case 0x40:		/* '@'  */
	case 0x24:		/* '$'  */
		return (1);
	default:
		return (0);
	}
}

static int
labellen(const unsigned char *lp)
{
	int bitlen;
	unsigned char l = *lp;

	if((l & NS_CMPRSFLGS) == NS_CMPRSFLGS)
	{
		/* should be avoided by the caller */
		return (-1);
	}

	if((l & NS_CMPRSFLGS) == NS_TYPE_ELT)
	{
		if(l == DNS_LABELTYPE_BITSTRING)
		{
			if((bitlen = *(lp + 1)) == 0)
				bitlen = 256;
			return ((bitlen + 7) / 8 + 1);
		}

		return (-1);	/* unknwon ELT */
	}

	return (l);
}


/*
 * printable(ch)
 *      Thinking in noninternationalized USASCII (per the DNS spec),
 *      is this character visible and not a space when printed ?
 * return:
 *      boolean.
 */
static int
printable(int ch)
{
	return (ch > 0x20 && ch < 0x7f);
}

static int
irc_decode_bitstring(const char **cpp, char *dn, const char *eom)
{
	const char *cp = *cpp;
	char *beg = dn, tc;
	int b, blen, plen;

	if((blen = (*cp & 0xff)) == 0)
		blen = 256;
	plen = (blen + 3) / 4;
	plen += sizeof("\\[x/]") + (blen > 99 ? 3 : (blen > 9) ? 2 : 1);
	if(dn + plen >= eom)
		return (-1);

	cp++;
	dn += sprintf(dn, "\\[x");
	for(b = blen; b > 7; b -= 8, cp++)
		dn += sprintf(dn, "%02x", *cp & 0xff);
	if(b > 4)
	{
		tc = *cp++;
		dn += sprintf(dn, "%02x", tc & (0xff << (8 - b)));
	}
	else if(b > 0)
	{
		tc = *cp++;
		dn += sprintf(dn, "%1x", ((tc >> 4) & 0x0f) & (0x0f << (4 - b)));
	}
	dn += sprintf(dn, "/%d]", blen);

	*cpp = cp;
	return (dn - beg);
}

/*
 * irc_ns_name_pton(src, dst, dstsiz)
 *  Convert a ascii string into an encoded domain name as per RFC1035.
 * return:
 *  -1 if it fails
 *  1 if string was fully qualified
 *  0 is string was not fully qualified
 * notes:
 *  Enforces label and domain length limits.
 */
static int
irc_ns_name_pton(const char *src, unsigned char *dst, size_t dstsiz)
{
	unsigned char *label, *bp, *eom;
	char *cp;
	int c, n, escaped, e = 0;

	escaped = 0;
	bp = dst;
	eom = dst + dstsiz;
	label = bp++;


	while((c = *src++) != 0)
	{
		if(escaped)
		{
			if(c == '[')
			{	/* start a bit string label */
				if((cp = strchr(src, ']')) == NULL)
				{
					errno = EINVAL;	/* ??? */
					return (-1);
				}
				if((e = irc_encode_bitsring(&src,
							    cp + 2,
							    &label, &bp, (const char *) eom)) != 0)
				{
					errno = e;
					return (-1);
				}
				escaped = 0;
				label = bp++;
				if((c = *src++) == 0)
					goto done;
				else if(c != '.')
				{
					errno = EINVAL;
					return (-1);
				}
				continue;
			}
			else if((cp = strchr(digits, c)) != NULL)
			{
				n = (cp - digits) * 100;
				if((c = *src++) == 0 || (cp = strchr(digits, c)) == NULL)
				{
					errno = EMSGSIZE;
					return (-1);
				}
				n += (cp - digits) * 10;
				if((c = *src++) == 0 || (cp = strchr(digits, c)) == NULL)
				{
					errno = EMSGSIZE;
					return (-1);
				}
				n += (cp - digits);
				if(n > 255)
				{
					errno = EMSGSIZE;
					return (-1);
				}
				c = n;
			}
			escaped = 0;
		}
		else if(c == '\\')
		{
			escaped = 1;
			continue;
		}
		else if(c == '.')
		{
			c = (bp - label - 1);
			if((c & NS_CMPRSFLGS) != 0)
			{	/* Label too big. */
				errno = EMSGSIZE;
				return (-1);
			}
			if(label >= eom)
			{
				errno = EMSGSIZE;
				return (-1);
			}
			*label = c;
			/* Fully qualified ? */
			if(*src == '\0')
			{
				if(c != 0)
				{
					if(bp >= eom)
					{
						errno = EMSGSIZE;
						return (-1);
					}
					*bp++ = '\0';
				}
				if((bp - dst) > NS_MAXCDNAME)
				{
					errno = EMSGSIZE;
					return (-1);
				}
				return (1);
			}
			if(c == 0 || *src == '.')
			{
				errno = EMSGSIZE;
				return (-1);
			}
			label = bp++;
			continue;
		}
		if(bp >= eom)
		{
			errno = EMSGSIZE;
			return (-1);
		}
		*bp++ = (unsigned char) c;
	}
	c = (bp - label - 1);
	if((c & NS_CMPRSFLGS) != 0)
	{			/* Label too big. */
		errno = EMSGSIZE;
		return (-1);
	}
      done:
	if(label >= eom)
	{
		errno = EMSGSIZE;
		return (-1);
	}
	*label = c;
	if(c != 0)
	{
		if(bp >= eom)
		{
			errno = EMSGSIZE;
			return (-1);
		}
		*bp++ = 0;
	}

	if((bp - dst) > NS_MAXCDNAME)
	{			/* src too big */
		errno = EMSGSIZE;
		return (-1);
	}

	return (0);
}

/*
 * irc_ns_name_pack(src, dst, dstsiz, dnptrs, lastdnptr)
 *  Pack domain name 'domain' into 'comp_dn'.
 * return:
 *  Size of the compressed name, or -1.
 * notes:
 *  'dnptrs' is an array of pointers to previous compressed names.
 *  dnptrs[0] is a pointer to the beginning of the message. The array
 *  ends with NULL.
 *  'lastdnptr' is a pointer to the end of the array pointed to
 *  by 'dnptrs'.
 * Side effects:
 *  The list of pointers in dnptrs is updated for labels inserted into
 *  the message as we compress the name.  If 'dnptr' is NULL, we don't
 *  try to compress names. If 'lastdnptr' is NULL, we don't update the
 *  list.
 */
static int
irc_ns_name_pack(const unsigned char *src, unsigned char *dst, int dstsiz,
		 const unsigned char **dnptrs, const unsigned char **lastdnptr)
{
	unsigned char *dstp;
	const unsigned char **cpp, **lpp, *eob, *msg;
	const unsigned char *srcp;
	int n, l, first = 1;

	srcp = src;
	dstp = dst;
	eob = dstp + dstsiz;
	lpp = cpp = NULL;
	if(dnptrs != NULL)
	{
		if((msg = *dnptrs++) != NULL)
		{
			for(cpp = dnptrs; *cpp != NULL; cpp++)
				(void) NULL;
			lpp = cpp;	/* end of list to search */
		}
	}
	else
		msg = NULL;

	/* make sure the domain we are about to add is legal */
	l = 0;
	do
	{
		int l0;

		n = *srcp;
		if((n & NS_CMPRSFLGS) == NS_CMPRSFLGS)
		{
			errno = EMSGSIZE;
			return (-1);
		}
		if((l0 = labellen(srcp)) < 0)
		{
			errno = EINVAL;
			return (-1);
		}
		l += l0 + 1;
		if(l > NS_MAXCDNAME)
		{
			errno = EMSGSIZE;
			return (-1);
		}
		srcp += l0 + 1;
	}
	while(n != 0);

	/* from here on we need to reset compression pointer array on error */
	srcp = src;
	do
	{
		/* Look to see if we can use pointers. */
		n = *srcp;
		if(n != 0 && msg != NULL)
		{
			l = irc_dn_find(srcp, msg, (const unsigned char *const *) dnptrs,
					(const unsigned char *const *) lpp);
			if(l >= 0)
			{
				if(dstp + 1 >= eob)
				{
					goto cleanup;
				}
				*dstp++ = (l >> 8) | NS_CMPRSFLGS;
				*dstp++ = l % 256;
				return (dstp - dst);
			}
			/* Not found, save it. */
			if(lastdnptr != NULL && cpp < lastdnptr - 1 &&
			   (dstp - msg) < 0x4000 && first)
			{
				*cpp++ = dstp;
				*cpp = NULL;
				first = 0;
			}
		}
		/* copy label to buffer */
		if((n & NS_CMPRSFLGS) == NS_CMPRSFLGS)
		{
			/* Should not happen. */
			goto cleanup;
		}
		n = labellen(srcp);
		if(dstp + 1 + n >= eob)
		{
			goto cleanup;
		}
		memcpy(dstp, srcp, n + 1);
		srcp += n + 1;
		dstp += n + 1;
	}
	while(n != 0);

	if(dstp > eob)
	{
	      cleanup:
		if(msg != NULL)
			*lpp = NULL;
		errno = EMSGSIZE;
		return (-1);
	}
	return (dstp - dst);
}

static int
irc_ns_name_compress(const char *src, unsigned char *dst, size_t dstsiz,
		     const unsigned char **dnptrs, const unsigned char **lastdnptr)
{
	unsigned char tmp[NS_MAXCDNAME];

	if(irc_ns_name_pton(src, tmp, sizeof tmp) == -1)
		return (-1);
	return (irc_ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
}

static int
irc_encode_bitsring(const char **bp, const char *end, unsigned char **labelp,
		    unsigned char **dst, const char *eom)
{
	int afterslash = 0;
	const char *cp = *bp;
	char *tp, c;
	const char *beg_blen;
	char *end_blen = NULL;
	int value = 0, count = 0, tbcount = 0, blen = 0;

	beg_blen = end_blen = NULL;

	/* a bitstring must contain at least 2 characters */
	if(end - cp < 2)
		return (EINVAL);

	/* XXX: currently, only hex strings are supported */
	if(*cp++ != 'x')
		return (EINVAL);
	if(!isxdigit((*cp) & 0xff))	/* reject '\[x/BLEN]' */
		return (EINVAL);

	for(tp = (char *) (dst + 1); cp < end && tp < eom; cp++)
	{
		switch ((c = *cp))
		{
		case ']':	/* end of the bitstring */
			if(afterslash)
			{
				if(beg_blen == NULL)
					return (EINVAL);
				blen = (int) strtol(beg_blen, &end_blen, 10);
				if(*end_blen != ']')
					return (EINVAL);
			}
			if(count)
				*tp++ = ((value << 4) & 0xff);
			cp++;	/* skip ']' */
			goto done;
		case '/':
			afterslash = 1;
			break;
		default:
			if(afterslash)
			{
				if(!isdigit(c & 0xff))
					return (EINVAL);
				if(beg_blen == NULL)
				{

					if(c == '0')
					{
						/* blen never begings with 0 */
						return (EINVAL);
					}
					beg_blen = cp;
				}
			}
			else
			{
				if(!isxdigit(c & 0xff))
					return (EINVAL);
				value <<= 4;
				value += digitvalue[(int) c];
				count += 4;
				tbcount += 4;
				if(tbcount > 256)
					return (EINVAL);
				if(count == 8)
				{
					*tp++ = value;
					count = 0;
				}
			}
			break;
		}
	}
      done:
	if(cp >= end || tp >= eom)
		return (EMSGSIZE);

	/*
	 * bit length validation:
	 * If a <length> is present, the number of digits in the <bit-data>
	 * MUST be just sufficient to contain the number of bits specified
	 * by the <length>. If there are insignificant bits in a final
	 * hexadecimal or octal digit, they MUST be zero.
	 * RFC 2673, Section 3.2.
	 */
	if(blen > 0)
	{
		int traillen;

		if(((blen + 3) & ~3) != tbcount)
			return (EINVAL);
		traillen = tbcount - blen;	/* between 0 and 3 */
		if(((value << (8 - traillen)) & 0xff) != 0)
			return (EINVAL);
	}
	else
		blen = tbcount;
	if(blen == 256)
		blen = 0;

	/* encode the type and the significant bit fields */
	**labelp = DNS_LABELTYPE_BITSTRING;
	**dst = blen;

	*bp = cp;
	*dst = (unsigned char *) tp;

	return (0);
}

/*
 * dn_find(domain, msg, dnptrs, lastdnptr)
 *  Search for the counted-label name in an array of compressed names.
 * return:
 *  offset from msg if found, or -1.
 * notes:
 *  dnptrs is the pointer to the first name on the list,
 *  not the pointer to the start of the message.
 */
static int
irc_dn_find(const unsigned char *domain, const unsigned char *msg,
	    const unsigned char *const *dnptrs, const unsigned char *const *lastdnptr)
{
	const unsigned char *dn, *cp, *sp;
	const unsigned char *const *cpp;
	unsigned int n;

	for(cpp = dnptrs; cpp < lastdnptr; cpp++)
	{
		sp = *cpp;
		/*
		 * terminate search on:
		 * root label
		 * compression pointer
		 * unusable offset
		 */
		while(*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 && (sp - msg) < 0x4000)
		{
			dn = domain;
			cp = sp;
			while((n = *cp++) != 0)
			{
				/*
				 * check for indirection
				 */
				switch (n & NS_CMPRSFLGS)
				{
				case 0:	/* normal case, n == len */
					n = labellen(cp - 1);	/* XXX */

					if(n != *dn++)
						goto next;

					for((void) NULL; n > 0; n--)
						if(mklower(*dn++) != mklower(*cp++))
							goto next;
					/* Is next root for both ? */
					if(*dn == '\0' && *cp == '\0')
						return (sp - msg);
					if(*dn)
						continue;
					goto next;
				case NS_CMPRSFLGS:	/* indirection */
					cp = msg + (((n & 0x3f) << 8) | *cp);
					break;

				default:	/* illegal type */
					errno = EMSGSIZE;
					return (-1);
				}
			}
		      next:;
			sp += *sp + 1;
		}
	}
	errno = ENOENT;
	return (-1);
}

/*
 *  *  Thinking in noninternationalized USASCII (per the DNS spec),
 *   *  convert this character to lower case if it's upper case.
 *    */
static int
mklower(int ch)
{
	if(ch >= 0x41 && ch <= 0x5A)
		return (ch + 0x20);

	return (ch);
}

/* From resolv/mkquery.c */

/*
 * Form all types of queries.
 * Returns the size of the result or -1.
 */
int
irc_res_mkquery(const char *dname,	/* domain name */
		int class, int type,	/* class and type of query */
		unsigned char *buf,	/* buffer to put query */
		int buflen)	/* size of buffer */
{
	HEADER *hp;
	unsigned char *cp;
	int n;
	unsigned char *dnptrs[20], **dpp, **lastdnptr;

	/*
	 * Initialize header fields.
	 */
	if((buf == NULL) || (buflen < HFIXEDSZ))
		return (-1);
	memset(buf, 0, HFIXEDSZ);
	hp = (HEADER *) buf;

	hp->id = 0;
	hp->opcode = QUERY;
	hp->rd = 1;		/* recurse */
	hp->rcode = NO_ERRORS;
	cp = buf + HFIXEDSZ;
	buflen -= HFIXEDSZ;
	dpp = dnptrs;
	*dpp++ = buf;
	*dpp++ = NULL;
	lastdnptr = dnptrs + sizeof dnptrs / sizeof dnptrs[0];

	if((buflen -= QFIXEDSZ) < 0)
		return (-1);
	if((n = irc_dn_comp(dname, cp, buflen, dnptrs, lastdnptr)) < 0)
		return (-1);

	cp += n;
	buflen -= n;
	IRC_NS_PUT16(type, cp);
	IRC_NS_PUT16(class, cp);
	hp->qdcount = htons(1);

	return (cp - buf);
}
